Coverage contour and interference thresholds for channel assignment

ABSTRACT

Aspects of the present disclosure relate to methods and apparatus for improving coverage contour and interference thresholds for general authorized access (GAA) channel assignment in a wireless communications environment.

CLAIM OF PRIORITY UNDER 35 U.S.C. § 119

This application claims benefit of U.S. Provisional Patent Application Ser. No. 62/417,242, filed Nov. 3, 2016, which is herein incorporated by reference in its entirety as if fully set forth below and for all applicable purposes.

FIELD OF THE DISCLOSURE

Certain aspects of the present disclosure generally relate to wireless communications and, more particularly, to techniques for improving coverage contour and interference thresholds for general authorized access (GAA) channel assignment.

DESCRIPTION OF RELATED ART

Wireless communication systems are widely deployed to provide various types of communication content such as voice, data, video, and the like, and deployments are likely to increase with introduction of new data oriented systems such as Long Term Evolution (LTE) systems. Wireless communication systems may be multiple-access systems capable of supporting communication with multiple users by sharing the available system resources (e.g., bandwidth and transmit power). Examples of such multiple-access systems include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, 3GPP Long Term Evolution (LTE) systems, and other orthogonal frequency division multiple access (OFDMA) systems.

Generally, a wireless multiple-access communication system can simultaneously support communication for multiple wireless terminals (also known as user equipments (UEs), user terminals, or access terminals (ATs)). Each terminal communicates with one or more base stations (also known as access points (APs), eNodeBs, or eNBs) via transmissions on forward and reverse links. The forward link (also referred to as a downlink or DL) refers to the communication link from the base stations to the terminals, and the reverse link (also referred to as an uplink or UL) refers to the communication link from the terminals to the base stations. These communication links may be established via single-in-single-out, single-in-multiple out, multiple-in-single-out, or multiple-in-multiple-out (MIMO) systems.

Newer multiple access systems, for example, LTE, deliver faster data throughput than older technologies. Faster downlink rates, in turn, have sparked a greater demand for higher-bandwidth content, such as high-resolution graphics and video, for use on or with mobile devices. Therefore, demand for bandwidth on wireless communications systems continues to increase despite availability of higher data throughput over wireless interfaces, and this trend is likely to continue. However, wireless spectrum is a limited and regulated resource. Therefore, new approaches are needed in wireless communications to more fully utilize this limited resource and satisfy consumer demand.

SUMMARY

The systems, methods, and devices of the disclosure each have several aspects, no single one of which is solely responsible for its desirable attributes. Without limiting the scope of this disclosure as expressed by the claims which follow, some features will now be discussed briefly. After considering this discussion, and particularly after reading the section entitled “DETAILED DESCRIPTION” one will understand how the features of this disclosure provide advantages that include improved communications between access points and stations in a wireless network.

Certain aspects of the present disclosure generally relate to techniques for improving coverage contour and interference thresholds for general authorized access (GAA) channel assignment.

Certain aspects of the present disclosure provide a method of assigning channels in a wireless communications environment. The method generally includes determining a coverage contour threshold and an interference threshold for each entity of a plurality of entities in the wireless communications environment, deciding whether a first entity and a second entity overlap in coverage based on the coverage contour threshold and the interference threshold for the first entity and the second entity, wherein the first entity and the second entity overlap if interference from the first entity is greater than the interference threshold for the second entity at any point at a boundary of or inside the coverage contour threshold of the second entity, and selecting a channel assignment for the first entity and the second entity based on the decision, wherein determining a channel assignment for the first entity and the second entity comprises assigning the first entity and the second entity orthogonal channels if the first entity and the second entity overlap in coverage.

Certain aspects of the present disclosure provide an apparatus for assigning channels in a wireless communications environment. The apparatus generally includes at least one processor configured to determine a coverage contour threshold and an interference threshold for each entity of a plurality of entities in the wireless communications environment, decide whether a first entity and a second entity overlap in coverage based on the coverage contour threshold and the interference threshold for the first entity and the second entity, wherein the first entity and the second entity overlap if interference from the first entity is greater than the interference threshold for the second entity at any point at a boundary of or inside the coverage contour threshold of the second entity, and select a channel assignment for the first entity and the second entity based on the decision, wherein selecting a channel assignment for the first entity and the second entity comprises assigning the first entity and the second entity orthogonal channels if the first entity and the second entity overlap in coverage. The apparatus also generally includes a memory coupled with the at least one processor.

Certain aspects of the present disclosure provide an apparatus for assigning channels in a wireless communications environment. The apparatus generally includes means for determining a coverage contour threshold and an interference threshold for each entity of a plurality of entities in the wireless communications environment, means for deciding whether a first entity and a second entity overlap in coverage based on the coverage contour threshold and the interference threshold for the first entity and the second entity, wherein the first entity and the second entity overlap if interference from the first entity is greater than the interference threshold for the second entity at any point at a boundary of or inside the coverage contour threshold of the second entity, and means for selecting a channel assignment for the first entity and the second entity based on the decision, wherein selecting a channel assignment for the first entity and the second entity comprises assigning the first entity and the second entity orthogonal channels if the first entity and the second entity overlap in coverage.

Certain aspects of the present disclosure provide an apparatus for assigning channels in a wireless communications environment. The apparatus generally includes instructions that, when executed by at least one processor, configure the at least one processor to determine a coverage contour threshold and an interference threshold for each entity of a plurality of entities in the wireless communications environment, decide whether a first entity and a second entity overlap in coverage based on the coverage contour threshold and the interference threshold for the first entity and the second entity, wherein the first entity and the second entity overlap if interference from the first entity is greater than the interference threshold for the second entity at any point at a boundary of or inside the coverage contour threshold of the second entity, and select a channel assignment for the first entity and the second entity based on the decision, wherein selecting a channel assignment for the first entity and the second entity comprises assigning the first entity and the second entity orthogonal channels if the first entity and the second entity overlap in coverage.

Numerous other aspects are provided including methods, apparatus, systems, computer program products, computer-readable medium, and processing systems. To the accomplishment of the foregoing and related ends, the one or more aspects comprise the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative features of the one or more aspects. These features are indicative, however, of but a few of the various ways in which the principles of various aspects may be employed, and this description is intended to include all such aspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above-recited features of the present disclosure can be understood in detail, a more particular description, briefly summarized above, may be had by reference to aspects, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only certain typical aspects of this disclosure and are therefore not to be considered limiting of its scope, for the description may admit to other equally effective aspects.

FIG. 1 is a diagram illustrating an example of a network architecture, in accordance with certain aspects of the disclosure.

FIG. 2 is a diagram illustrating an example of an access network, in accordance with certain aspects of the disclosure.

FIG. 3 is a diagram illustrating an example of a DL frame structure in LTE, in accordance with certain aspects of the disclosure.

FIG. 4 is a diagram illustrating an example of an UL frame structure in LTE, in accordance with certain aspects of the disclosure.

FIG. 5 is a diagram illustrating an example of a radio protocol architecture for the user and control plane, in accordance with certain aspects of the disclosure.

FIG. 6 is a diagram illustrating an example of an evolved Node B and user equipment in an access network, in accordance with certain aspects of the disclosure.

FIG. 7 is a block diagram showing aspects of an Authorized Shared Access (ASA) controller coupled to different wireless communication systems including one primary user and one secondary user, in accordance with certain aspects of the disclosure.

FIG. 8 is a block diagram showing aspects of an ASA controller coupled to different wireless communication systems including one primary user and multiple secondary users, in accordance with certain aspects of the disclosure.

FIG. 9 illustrates an example architecture of a spectrum sharing system, in accordance with certain aspects of the disclosure.

FIG. 10 illustrates example operations for assigning channels to a plurality of networks in a wireless communications environment, in accordance with certain aspects of the present disclosure.

FIG. 11 shows a communication device illustrating means for performing operations for assigning channels, according to certain aspects of the present disclosure.

To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one aspect may be beneficially utilized on other aspects without specific recitation.

DETAILED DESCRIPTION

Aspects of the present disclosure provide techniques for assigning channels to networks (e.g., network operators) co-existing in the same spectrum, for example, a 3.5 GHz spectrum, and that may be subject to interference limitations with respect to other networks in the same spectrum. For example, aspects of the present disclosure provide techniques for improving coverage contour and interference thresholds for general authorized access (GAA) channel assignment (e.g., within the 3.5 GHz spectrum). As will be explained in greater detail below, in some cases, these coverage and interference thresholds may be determined as a function of interference and throughput of an assigned channel bandwidth.

The techniques described herein may be used for various wireless communication networks such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA and other networks. The terms “network” and “system” are often used interchangeably. A CDMA network may implement a radio technology such as universal terrestrial radio access (UTRA), cdma2000, etc. UTRA includes wideband CDMA (WCDMA), time division synchronous CDMA (TD-SCDMA), and other variants of CDMA. cdma2000 covers IS-2000, IS-95 and IS-856 standards. A TDMA network may implement a radio technology such as global system for mobile communications (GSM). An OFDMA network may implement a radio technology such as evolved UTRA (E-UTRA), ultra mobile broadband (UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDM®, etc. UTRA and E-UTRA are part of universal mobile telecommunication system (UMTS). 3GPP Long Term Evolution (LTE) and LTE-Advanced (LTE-A), in both frequency division duplex (FDD) and time division duplex (TDD), are new releases of UMTS that use E-UTRA, which employs OFDMA on the downlink and SC-FDMA on the uplink. UTRA, E-UTRA, UMTS, LTE, LTE-A and GSM are described in documents from an organization named “3rd Generation Partnership Project” (3GPP). cdma2000 and UMB are described in documents from an organization named “3rd Generation Partnership Project 2” (3GPP2). The techniques described herein may be used for the wireless networks and radio technologies mentioned above as well as other wireless networks and radio technologies. For clarity, certain aspects of the techniques are described below for LTE/LTE-Advanced, and LTE/LTE-Advanced terminology is used in much of the description below. LTE and LTE-A are referred to generally as LTE.

A wireless communication network may include a number of base stations that can support communication for a number of wireless devices. Wireless devices may include user equipments (UEs). Some examples of UEs may include cellular phones, smart phones, personal digital assistants (PDAs), wireless modems, handheld devices, tablets, laptop computers, netbooks, smartbooks, ultrabooks, wearables (e.g., smart watch, smart bracelet, smart glasses, smart ring, smart clothing), etc.

System designs may support various time-frequency reference signals for the downlink and uplink to facilitate beamforming and other functions. A reference signal is a signal generated based on known data and may also be referred to as a pilot, preamble, training signal, sounding signal, and the like. A reference signal may be used by a receiver for various purposes such as channel estimation, coherent demodulation, channel quality measurement, signal strength measurement, and the like. MIMO systems using multiple antennas generally provide for coordination of sending of reference signals between antennas; however, LTE systems do not in general provide for coordination of sending of reference signals from multiple base stations or eNBs.

In some implementations, a system may use time division duplexing (TDD). For TDD, the downlink and uplink share the same frequency spectrum or channel, and downlink and uplink transmissions are sent on the same frequency spectrum. The downlink channel response may thus be correlated with the uplink channel response. Reciprocity may allow a downlink channel to be estimated based on transmissions sent via the uplink. These uplink transmissions may be reference signals or uplink control channels (which may be used as reference symbols after demodulation). The uplink transmissions may allow for estimation of a space-selective channel via multiple antennas.

In LTE implementations, orthogonal frequency division multiplexing (OFDM) is used for the downlink—that is, from a base station, access point or eNodeB (eNB) to a user terminal or UE. Use of OFDM meets the LTE requirement for spectrum flexibility and enables cost-efficient solutions for very wide carriers with high peak rates, and is a well-established technology. For example, OFDM is used in standards such as IEEE 802.11a/g, 802.16, High Performance Radio LAN-2 (HIPERLAN-2, wherein LAN stands for Local Area Network) standardized by the European Telecommunications Standards Institute (ETSI), Digital Video Broadcasting (DVB) published by the Joint Technical Committee of ETSI, and other standards.

Time frequency physical resource blocks (also denoted here in as resource blocks or “RBs” for brevity) may be defined in OFDM systems as groups of transport carriers (e.g., sub-carriers) or intervals that are assigned to transport data. The RBs are defined over a time and frequency period. Resource blocks are comprised of time-frequency resource elements (also denoted here in as resource elements or “REs” for brevity), which may be defined by indices of time and frequency in a slot. Additional details of LTE RBs and REs are described in the 3GPP specifications, such as, for example, 3GPP TS 36.211.

UMTS LTE supports scalable carrier bandwidths from 20 MHz down to 1.4 MHZ. In LTE, an RB is defined as 12 sub-carriers when the subcarrier bandwidth is 15 kHz, or 24 sub-carriers when the sub-carrier bandwidth is 7.5 kHz. In an exemplary implementation, in the time domain there is a defined radio frame that is 10 ms long and consists of 10 subframes of 1 millisecond (ms) each. Every subframe consists of 2 slots, where each slot is 0.5 ms. The subcarrier spacing in the frequency domain in this case is 15 kHz. Twelve of these subcarriers together (per slot) constitute an RB, so in this implementation one resource block is 180 kHz. Six Resource blocks fit in a carrier of 1.4 MHz and 100 resource blocks fit in a carrier of 20 MHz.

Various other aspects and features of the disclosure are further described below. It should be apparent that the teachings herein may be embodied in a wide variety of forms and that any specific structure, function, or both being disclosed herein is merely representative and not limiting. Based on the teachings herein one of an ordinary level of skill in the art should appreciate that an aspect disclosed herein may be implemented independently of any other aspects and that two or more of these aspects may be combined in various ways. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth herein. In addition, such an apparatus may be implemented or such a method may be practiced using other structure, functionality, or structure and functionality in addition to or other than one or more of the aspects set forth herein. For example, a method may be implemented as part of a system, device, apparatus, and/or as instructions stored on a computer-readable medium for execution on a processor or computer. Furthermore, an aspect may comprise at least one element of a claim.

It is noted that while aspects may be described herein using terminology commonly associated with 3G and/or 4G wireless technologies, aspects of the present disclosure can be applied in other generation-based communication systems, such as 5G and later.

An Example Wireless Communications System

FIG. 1 is a diagram illustrating an LTE network architecture 100 in which aspects of the present disclosure may be practiced. For example, a core network entity (not shown) may determine coverage contour and interference thresholds for networks operating in a wireless communications environment so as to optimally reduce interference seen in these networks while maintaining an acceptable channel throughput (e.g., bandwidth).

The LTE network architecture 100 may be referred to as an Evolved Packet System (EPS) 100. The EPS 100 may include one or more user equipment (UE) 102, an Evolved UMTS Terrestrial Radio Access Network (E-UTRAN) 104, an Evolved Packet Core (EPC) 110, a Home Subscriber Server (HSS) 120, and an Operator's IP Services 122. The EPS can interconnect with other access networks, but for simplicity those entities/interfaces are not shown. Exemplary other access networks may include an IP Multimedia Subsystem (IMS) PDN, Internet PDN, Administrative PDN (e.g., Provisioning PDN), carrier-specific PDN, operator-specific PDN, and/or GPS PDN. As shown, the EPS provides packet-switched services, however, as those skilled in the art will readily appreciate, the various concepts presented throughout this disclosure may be extended to networks providing circuit-switched services.

The E-UTRAN includes the evolved Node B (eNB) 106 and other eNBs 108. The eNB 106 provides user and control plane protocol terminations toward the UE 102. The eNB 106 may be connected to the other eNBs 108 via an X2 interface (e.g., backhaul). The eNB 106 may also be referred to as a base station, a base transceiver station, a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS), an extended service set (ESS), an access point, or some other suitable terminology. The eNB 106 may provide an access point to the EPC 110 for a UE 102. Examples of UEs 102 include a cellular phone, a smart phone, a session initiation protocol (SIP) phone, a laptop, a personal digital assistant (PDA), a satellite radio, a global positioning system, a multimedia device, a video device, a digital audio player (e.g., MP3 player), a camera, a game console, a tablet, a netbook, a smart book, an ultrabook, a drone, a robot, a sensor, a monitor, a meter, or any other similar functioning device. The UE 102 may also be referred to by those skilled in the art as a mobile station, a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, a user agent, a mobile client, a client, or some other suitable terminology.

The eNB 106 is connected by an S1 interface to the EPC 110. The EPC 110 includes a Mobility Management Entity (MME) 112, other MMEs 114, a Serving Gateway 116, and a Packet Data Network (PDN) Gateway 118. The MME 112 is the control node that processes the signaling between the UE 102 and the EPC 110. Generally, the MME 112 provides bearer and connection management. All user IP packets are transferred through the Serving Gateway 116, which itself is connected to the PDN Gateway 118. The PDN Gateway 118 provides UE IP address allocation as well as other functions. The PDN Gateway 118 is connected to the Operator's IP Services 122. The Operator's IP Services 122 may include, for example, the Internet, the Intranet, an IP Multimedia Subsystem (IMS), and a PS (packet-switched) Streaming Service (PSS). In this manner, the UE 102 may be coupled to the PDN through the LTE network.

FIG. 2 is a diagram illustrating an example of an access network 200 in an LTE network architecture in which aspects of the present disclosure may be practiced. For example, a core network entity (not shown) may determine coverage contour and interference thresholds for the access network 200 operating in a wireless communications environment so as to optimally reduce interference seen in the access network 200 (e.g., caused by other networks in the wireless communications environment) while maintaining an acceptable channel throughput (e.g., bandwidth) for the access network 200.

In this example, the access network 200 is divided into a number of cellular regions (cells) 202. One or more lower power class eNBs 208 may have cellular regions 210 that overlap with one or more of the cells 202. A lower power class eNB 208 may be referred to as a remote radio head (RRH). The lower power class eNB 208 may be a femto cell (e.g., home eNB (HeNB)), pico cell, or micro cell. The macro eNBs 204 are each assigned to a respective cell 202 and are configured to provide an access point to the EPC 110 for all the UEs 206 in the cells 202. There is no centralized controller in this example of an access network 200, but a centralized controller may be used in alternative configurations. The eNBs 204 are responsible for all radio related functions including radio bearer control, admission control, mobility control, scheduling, security, and connectivity to the serving gateway 116. The network 200 may also include one or more relays (not shown). According to one application, a UE may serve as a relay.

The modulation and multiple access scheme employed by the access network 200 may vary depending on the particular telecommunications standard being deployed. In LTE applications, OFDM is used on the DL and SC-FDMA is used on the UL to support both frequency division duplexing (FDD) and time division duplexing (TDD). As those skilled in the art will readily appreciate from the detailed description to follow, the various concepts presented herein are well suited for LTE applications. However, these concepts may be readily extended to other telecommunication standards employing other modulation and multiple access techniques. By way of example, these concepts may be extended to Evolution-Data Optimized (EV-DO) or Ultra Mobile Broadband (UMB). EV-DO and UMB are air interface standards promulgated by the 3rd Generation Partnership Project 2 (3GPP2) as part of the CDMA2000 family of standards and employs CDMA to provide broadband Internet access to mobile stations. These concepts may also be extended to Universal Terrestrial Radio Access (UTRA) employing Wideband-CDMA (W-CDMA) and other variants of CDMA, such as TD-SCDMA; Global System for Mobile Communications (GSM) employing TDMA; and Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, and Flash-OFDM employing OFDMA. UTRA, E-UTRA, UMTS, LTE and GSM are described in documents from the 3GPP organization. CDMA2000 and UMB are described in documents from the 3GPP2 organization. The actual wireless communication standard and the multiple access technology employed will depend on the specific application and the overall design constraints imposed on the system.

The eNBs 204 may have multiple antennas supporting MIMO technology. The use of MIMO technology enables the eNBs 204 to exploit the spatial domain to support spatial multiplexing, beamforming, and transmit diversity. Spatial multiplexing may be used to transmit different streams of data simultaneously on the same frequency. The data streams may be transmitted to a single UE 206 to increase the data rate or to multiple UEs 206 to increase the overall system capacity. This is achieved by spatially precoding each data stream (e.g., applying a scaling of an amplitude and a phase) and then transmitting each spatially precoded stream through multiple transmit antennas on the DL. The spatially precoded data streams arrive at the UE(s) 206 with different spatial signatures, which enables each of the UE(s) 206 to recover the one or more data streams destined for that UE 206. On the UL, each UE 206 transmits a spatially precoded data stream, which enables the eNB 204 to identify the source of each spatially precoded data stream.

Spatial multiplexing is generally used when channel conditions are good. When channel conditions are less favorable, beamforming may be used to focus the transmission energy in one or more directions. This may be achieved by spatially precoding the data for transmission through multiple antennas. To achieve good coverage at the edges of the cell, a single stream beamforming transmission may be used in combination with transmit diversity.

In the detailed description that follows, various aspects of an access network will be described with reference to a MIMO system supporting OFDM on the DL. OFDM is a spread-spectrum technique that modulates data over a number of subcarriers within an OFDM symbol. The subcarriers are spaced apart at precise frequencies. The spacing provides “orthogonality” that enables a receiver to recover the data from the subcarriers. In the time domain, a guard interval (e.g., cyclic prefix) may be added to each OFDM symbol to combat inter-OFDM-symbol interference. The UL may use SC-FDMA in the form of a DFT-spread OFDM signal to compensate for high peak-to-average power ratio (PAPR).

FIG. 3 is a diagram 300 illustrating an example of a DL frame structure in LTE. A frame (10 ms) may be divided into 10 equally sized sub-frames with indices of 0 through 9. Each sub-frame may include two consecutive time slots. A resource grid may be used to represent two time slots, each time slot including a resource block. The resource grid is divided into multiple resource elements. In LTE, a resource block contains 12 consecutive subcarriers in the frequency domain and, for a normal cyclic prefix in each OFDM symbol, 7 consecutive OFDM symbols in the time domain, or 84 resource elements. For an extended cyclic prefix, a resource block contains 6 consecutive OFDM symbols in the time domain and has 72 resource elements. Some of the resource elements, as indicated as R 302, R 304, include DL reference signals (DL-RS). The DL-RS include Cell-specific RS (CRS) (also sometimes called common RS) 302 and UE-specific RS (UE-RS) 304. UE-RS 304 are transmitted only on the resource blocks upon which the corresponding physical DL shared channel (PDSCH) is mapped. The number of bits carried by each resource element depends on the modulation scheme. Thus, the more resource blocks that a UE receives and the higher the modulation scheme, the higher the data rate for the UE.

In LTE, an eNB may send a primary synchronization signal (PSS) and a secondary synchronization signal (SSS) for each cell in the eNB. The primary and secondary synchronization signals may be sent in symbol periods 6 and 5, respectively, in each of subframes 0 and 5 of each radio frame with the normal cyclic prefix (CP). The synchronization signals may be used by UEs for cell detection and acquisition. The eNB may send a Physical Broadcast Channel (PBCH) in symbol periods 0 to 3 in slot 1 of subframe 0. The PBCH may carry certain system information.

The eNB may send a Physical Control Format Indicator Channel (PCFICH) in the first symbol period of each subframe. The PCFICH may convey the number of symbol periods (M) used for control channels, where M may be equal to 1, 2 or 3 and may change from subframe to subframe. M may also be equal to 4 for a small system bandwidth, e.g., with less than 10 resource blocks. The eNB may send a Physical HARQ Indicator Channel (PHICH) and a Physical Downlink Control Channel (PDCCH) in the first M symbol periods of each subframe. The PHICH may carry information to support hybrid automatic repeat request (HARQ). The PDCCH may carry information on resource allocation for UEs and control information for downlink channels. The eNB may send a Physical Downlink Shared Channel (PDSCH) in the remaining symbol periods of each subframe. The PDSCH may carry data for UEs scheduled for data transmission on the downlink.

The eNB may send the PSS, SSS, and PBCH in the center 1.08 MHz of the system bandwidth used by the eNB. The eNB may send the PCFICH and PHICH across the entire system bandwidth in each symbol period in which these channels are sent. The eNB may send the PDCCH to groups of UEs in certain portions of the system bandwidth. The eNB may send the PDSCH to specific UEs in specific portions of the system bandwidth. The eNB may send the PSS, SSS, PBCH, PCFICH, and PHICH in a broadcast manner to all UEs, may send the PDCCH in a unicast manner to specific UEs, and may also send the PDSCH in a unicast manner to specific UEs.

A number of resource elements may be available in each symbol period. Each resource element (RE) may cover one subcarrier in one symbol period and may be used to send one modulation symbol, which may be a real or complex value. Resource elements not used for a reference signal in each symbol period may be arranged into resource element groups (REGs). Each REG may include four resource elements in one symbol period. The PCFICH may occupy four REGs, which may be spaced approximately equally across frequency, in symbol period 0. The PHICH may occupy three REGs, which may be spread across frequency, in one or more configurable symbol periods. For example, the three REGs for the PHICH may all belong in symbol period 0 or may be spread in symbol periods 0, 1, and 2. The PDCCH may occupy 9, 18, 36, or 72 REGs, which may be selected from the available REGs, in the first M symbol periods, for example. Only certain combinations of REGs may be allowed for the PDCCH. In aspects of the present methods and apparatus, a subframe may include more than one PDCCH.

A UE may know the specific REGs used for the PHICH and the PCFICH. The UE may search different combinations of REGs for the PDCCH. The number of combinations to search is typically less than the number of allowed combinations for the PDCCH. An eNB may send the PDCCH to the UE in any of the combinations that the UE will search.

FIG. 4 is a diagram 400 illustrating an example of an UL frame structure in LTE. The available resource blocks for the UL may be partitioned into a data section and a control section. The control section may be formed at the two edges of the system bandwidth and may have a configurable size. The resource blocks in the control section may be assigned to UEs for transmission of control information. The data section may include all resource blocks not included in the control section. The UL frame structure results in the data section including contiguous subcarriers, which may allow a single UE to be assigned all of the contiguous subcarriers in the data section.

A UE may be assigned resource blocks 410 a, 410 b in the control section to transmit control information to an eNB. The UE may also be assigned resource blocks 420 a, 420 b in the data section to transmit data to the eNB. The UE may transmit control information in a physical UL control channel (PUCCH) on the assigned resource blocks in the control section. The UE may transmit only data or both data and control information in a physical UL shared channel (PUSCH) on the assigned resource blocks in the data section. A UL transmission may span both slots of a subframe and may hop across frequency.

A set of resource blocks may be used to perform initial system access and achieve UL synchronization in a physical random access channel (PRACH) 430. The PRACH 430 carries a random sequence and cannot carry any UL data/signaling. Each random access preamble occupies a bandwidth corresponding to six consecutive resource blocks. The starting frequency is specified by the network. That is, the transmission of the random access preamble is restricted to certain time and frequency resources. There is no frequency hopping for the PRACH. The PRACH attempt is carried in a single subframe (1 ms) or in a sequence of few contiguous subframes and a UE can make only a single PRACH attempt per frame (10 ms).

FIG. 5 is a diagram 500 illustrating an example of a radio protocol architecture for the user and control planes in LTE. The radio protocol architecture for the UE and the eNB is shown with three layers: Layer 1, Layer 2, and Layer 3. Layer 1 (L1 layer) is the lowest layer and implements various physical layer signal processing functions. The L1 layer will be referred to herein as the physical layer 506. Layer 2 (L2 layer) 508 is above the physical layer 506 and is responsible for the link between the UE and eNB over the physical layer 506.

In the user plane, the L2 layer 508 includes a media access control (MAC) sublayer 510, a radio link control (RLC) sublayer 512, and a packet data convergence protocol (PDCP) 514 sublayer, which are terminated at the eNB on the network side. Although not shown, the UE may have several upper layers above the L2 layer 508 including a network layer (e.g., IP layer) that is terminated at the PDN gateway 118 on the network side, and an application layer that is terminated at the other end of the connection (e.g., far end UE, server, etc.).

The PDCP sublayer 514 provides multiplexing between different radio bearers and logical channels. The PDCP sublayer 514 also provides header compression for upper layer data packets to reduce radio transmission overhead, security by ciphering the data packets, and handover support for UEs between eNBs. The RLC sublayer 512 provides segmentation and reassembly of upper layer data packets, retransmission of lost data packets, and reordering of data packets to compensate for out-of-order reception due to hybrid automatic repeat request (HARQ). The MAC sublayer 510 provides multiplexing between logical and transport channels. The MAC sublayer 510 is also responsible for allocating the various radio resources (e.g., resource blocks) in one cell among the UEs. The MAC sublayer 510 is also responsible for HARQ operations.

In the control plane, the radio protocol architecture for the UE and eNB is substantially the same for the physical layer 506 and the L2 layer 508 with the exception that there is no header compression function for the control plane. The control plane also includes a radio resource control (RRC) sublayer 516 in Layer 3 (L3 layer). The RRC sublayer 516 is responsible for obtaining radio resources (i.e., radio bearers) and for configuring the lower layers using RRC signaling between the eNB and the UE.

FIG. 6 is a block diagram of an eNB 610 in communication with a UE 650 in an access network, in which aspects of the present disclosure may be practiced. For example, a central entity (not shown) may evaluate an amount of transmission limitation imposed on each pair of channel and group of eNBs (e.g., eNBs 610) assigned to the respective channel. The central entity may assign a channel to each group of eNBs based on the evaluation. It may be noted that the central entity may be implemented by eNB 610 or UE 650.

In the DL, upper layer packets from the core network are provided to a controller/processor 675. The controller/processor 675 implements the functionality of the L2 layer, for example. In the DL, the controller/processor 675 provides header compression, ciphering, packet segmentation and reordering, multiplexing between logical and transport channels, and radio resource allocations to the UE 650 based on various priority metrics. The controller/processor 675 is also responsible for HARQ operations, retransmission of lost packets, and signaling to the UE 650.

The TX processor 616 implements various signal processing functions for the L1 layer (i.e., physical layer), for example. The signal processing functions includes coding and interleaving to facilitate forward error correction (FEC) at the UE 650 and mapping to signal constellations based on various modulation schemes (e.g., binary phase-shift keying (BPSK), quadrature phase-shift keying (QPSK), M-phase-shift keying (M-PSK), M-quadrature amplitude modulation (M-QAM)). The coded and modulated symbols are then split into parallel streams. Each stream is then mapped to an OFDM subcarrier, multiplexed with a reference signal (e.g., pilot) in the time and/or frequency domain, and then combined together using an Inverse Fast Fourier Transform (IFFT) to produce a physical channel carrying a time domain OFDM symbol stream. The OFDM stream is spatially precoded to produce multiple spatial streams. Channel estimates from a channel estimator 674 may be used to determine the coding and modulation scheme, as well as for spatial processing. The channel estimate may be derived from a reference signal and/or channel condition feedback transmitted by the UE 650. Each spatial stream is then provided to a different antenna 620 via a separate transmitter 618TX. Each transmitter 618TX modulates an RF carrier with a respective spatial stream for transmission.

At the UE 650, each receiver 654RX receives a signal through its respective antenna 652. Each receiver 654RX recovers information modulated onto an RF carrier and provides the information to the receiver (RX) processor 656. The RX processor 656 implements various signal processing functions of the L1 layer, for example. The RX processor 656 performs spatial processing on the information to recover any spatial streams destined for the UE 650. If multiple spatial streams are destined for the UE 650, they may be combined by the RX processor 656 into a single OFDM symbol stream. The RX processor 656 then converts the OFDM symbol stream from the time-domain to the frequency domain using a Fast Fourier Transform (FFT). The frequency domain signal comprises a separate OFDM symbol stream for each subcarrier of the OFDM signal. The symbols on each subcarrier, and the reference signal, is recovered and demodulated by determining the most likely signal constellation points transmitted by the eNB 610. These soft decisions may be based on channel estimates computed by the channel estimator 658. The soft decisions are then decoded and deinterleaved to recover the data and control signals that were originally transmitted by the eNB 610 on the physical channel. The data and control signals are then provided to the controller/processor 659.

The controller/processor 659 implements the L2 layer, for example. The controller/processor 659 can be associated with a memory 660 that stores program codes and data. The memory 660 may be referred to as a computer-readable medium. In the UL, the controller/processor 659 provides demultiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, control signal processing to recover upper layer packets from the core network. The upper layer packets are then provided to a data sink 662, which represents all the protocol layers above the L2 layer. Various control signals may also be provided to the data sink 662 for L3 processing. The controller/processor 659 is also responsible for error detection using an acknowledgement (ACK) and/or negative acknowledgement (NACK) protocol to support HARQ operations.

In the UL, a data source 667 is used to provide upper layer packets to the controller/processor 659, for example. The data source 667 represents all protocol layers above the L2 layer, for example. Similar to the functionality described in connection with the DL transmission by the eNB 610, the controller/processor 659 implements the L2 layer for the user plane and the control plane by providing header compression, ciphering, packet segmentation and reordering, and multiplexing between logical and transport channels based on radio resource allocations by the eNB 610, for example. The controller/processor 659 is also responsible for HARQ operations, retransmission of lost packets, and signaling to the eNB 610, for example.

Channel estimates derived by a channel estimator 658 from a reference signal or feedback transmitted by the eNB 610 may be used by the TX processor 668 to select the appropriate coding and modulation schemes, and to facilitate spatial processing. The spatial streams generated by the TX processor 668 are provided to different antenna 652 via separate transmitters 654TX. Each transmitter 654TX modulates an RF carrier with a respective spatial stream for transmission.

The UL transmission is processed at the eNB 610 in a manner similar to that described in connection with the receiver function at the UE 650. Each receiver 618RX receives a signal through its respective antenna 620. Each receiver 618RX recovers information modulated onto an RF carrier and provides the information to a RX processor 670. The RX processor 670 may implement the L1 layer, for example.

The controller/processor 675 implements the L2 layer, for example. The controller/processor 675 can be associated with a memory 676 that stores program codes and data. The memory 676 may be referred to as a computer-readable medium. In the UL, the control/processor 675 provides demultiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, control signal processing to recover upper layer packets from the UE 650. Upper layer packets from the controller/processor 675 may be provided to the core network. The controller/processor 675 is also responsible for error detection using an ACK and/or NACK protocol to support HARQ operations. The controllers/processors 675, 659 may direct the operations at the eNB 610 and the UE 650, respectively.

The controller/processor 675 and/or other processors, components and/or modules at the eNB 610 or the controller/processor 659 and/or other processors, components and/or modules at the UE 650 may perform or direct operations, for example, operations 1100 in FIG. 11, and/or other processes for the techniques described herein for assigning channels to groups of devices sharing bandwidth in presence of incumbent devices. In certain aspects, one or more of any of the components shown in FIG. 6 may be employed to perform example operations 1100, and/or other processes for the techniques described herein. The memories 660 and 676 may store data and program codes for the UE 650 and eNB 610 respectively, accessible and executable by one or more other components of the UE 650 and the eNB 610.

Example Authorized Shared Access for 3.5 GHz

Due to the explosive growth in mobile broadband traffic and its concomitant strain on limited spectrum resources, the Federal Communications Commission has adopted rules to allow commercial shared use of 150 MHz of spectrum in the 3550-3700 MHz (3.5 GHz) band for licensed and unlicensed use of the 3.5 GHz band for a wide variety of services.

Citizens Broadband Radio service (CBRS) is a tiered commercial radio service in 3.5 GHz in the U.S. A Spectrum Access System (SAS) may allocate channels within and across tiers, for example, according to aspects presented here (e.g., with reference to operations 1000 illustrated in FIG. 10). These tiers can include, in order of priority, (1) incumbent licensees; (2) Priority Access licensees (PALs); and (3) General Authorized Access (GAA) operators.

Authorized shared access (ASA) allocates, to a secondary user(s), portions of spectrum that are not continuously used by an incumbent system(s). The incumbent system may be referred to as an incumbent licensee, Tier 1 operator, primary licensee, or a primary user that is given a primary license for a band of frequencies. The incumbent system may not use the entire frequency band in all locations and/or at all times. The secondary user may be referred to as a secondary licensee or a secondary network. Aspects of the present disclosure are directed to an ASA implementation. Still, the ASA technology is not limited to the illustrated configurations as other configurations are also contemplated. The ASA spectrum refers to portion(s) of a spectrum that is not used by a primary user and has been licensed for use by a secondary user, such as an ASA operator. ASA spectrum availability may be specified by location, frequency, and/or time. It should be noted that the authorized shared access may also be referred to as licensed shared access (LSA).

A PAL is an authorization to use a channel (e.g., an unpaired 10 MHz channel) in the 3.5 GHz range in a geographic service area for a period (e.g., 3 years). The PAL geographic service area may be census tracts, which typically align with the borders of political boundaries such as cities or counties. PAL licensees can aggregate up to four PA channels in any census tract at any given time, and may obtain licenses in any available census tract. PALs may provide interference protection for Tier 1 incumbent licensees and accept interference from them; however, PALs may be entitled to interference protection from GAA operators.

The third tier, GAA, permits access to bandwidth (e.g., 80 MHz) of the 3.5 GHz band that is not assigned to a higher tier (i.e., incumbent licensees or PALs). GAA may be licensed “by rule,” meaning that entities that qualify to be FCC licensees may use FCC-authorized telecommunications equipment in the GAA band without having to obtain an individual spectrum license. GAA operators may receive no interference protection from PALs or Tier 1 operators, and may accept interference from them.

In order to facilitate the complex CBRS spectrum sharing process, a Spectrum Access System (“SAS”), which may be a highly automated frequency coordinator, can be used to assign frequencies in the 3.5 GHz band, for example, according to aspects presented herein. The SAS can also authorize and manage use of the CBRS spectrum, protect higher tier operations from interference, and maximize frequency capacity for all CBRS operators.

Example ASA Architecture

In one configuration, as shown in FIG. 7, an ASA architecture 700 includes an ASA controller 702 coupled to an incumbent network controller 712 of a primary user and an ASA network manager 714 of an ASA network. The primary user may be a primary ASA licensee and the ASA network may be a secondary user.

In one configuration, the incumbent network controller is a network entity operated by the primary user that controls and/or manages the network operating in the ASA spectrum. Furthermore, the ASA network manager may be a network entity operated by the ASA network operator that controls and/or manages an associated network, including but not limited to the devices operating in the ASA spectrum. Additionally, the secondary licensee may be a wireless network operator that has obtained an ASA license to use the ASA spectrum. Furthermore, in one configuration, the ASA controller is a network entity that receives information from the incumbent network controller on the available ASA spectrum that may be used by an ASA network. The ASA controller may also transmit control information to the ASA network manager to notify the ASA network manager of the available ASA spectrum.

In the present configuration, the incumbent network controller 712 is aware of the use of the ASA spectrum by the primary user at specified times and/or locations. The incumbent network controller 712 may provide information to the ASA controller 702 for the incumbent usage of the ASA spectrum. There are several methods that the incumbent network controller 712 can use to provide this information to the ASA controller 702. In one configuration, the incumbent network controller 712 provides a set of exclusion zones and/or exclusion times to the ASA controller 702. In another configuration, the incumbent network controller 712 specifies a threshold for allowed interference at a set of locations. The threshold for allowed interference may be referred to as incumbent protection information. In this configuration, the incumbent protection information is transmitted to the ASA controller 702 over an ASA-1 interface 716. Incumbent protection information may be stored by the ASA controller 702 in a database 706.

The ASA-1 interface refers to the interface between the primary user and the ASA controller. The ASA-2 interface refers to the interface between the ASA controller and the ASA network management system. Moreover, the ASA-3 interface refers to the interface between the ASA network manager and the ASA network elements. Furthermore, geographic sharing refers to an ASA sharing model in which the ASA network can operate throughout a geographic region for an extended period of time. The network is not permitted to operate in regions specified by exclusion zones.

The ASA controller 702 uses the information from the incumbent network controller 712 to determine the ASA spectrum that may be used by the ASA network. That is, the ASA controller 702 determines the ASA spectrum that may be used for a specific time and/or a specific location based on rules specified in a rules database 708. The rules database 708 may be accessed by an ASA processor 704 and stores the regulatory rules that are set by local regulations. These rules may not be modified by the ASA-1 or the ASA-2 interfaces, and may be updated by the individual or organization that manages the ASA controller 702. The available ASA spectrum, as calculated by the rules in the rules database 708, may be stored in the ASA spectrum availability database 710.

The ASA controller 702 may send information to the ASA network manager 714 on the available ASA spectrum via an ASA-2 interface 718, based on the spectrum availability database. The ASA network manager 714 may know or determine the geographic location of base stations under its control and also information about the transmission characteristics of these base stations, such as transmit power and/or supported frequencies of operation. The ASA network manager 714 may query the ASA controller 702 to discover the available ASA spectrum in a given location or a geographic region. Also, the ASA controller 702 may notify the ASA network manager 714 of any updates to the ASA spectrum availability in real-time. This allows the ASA controller 702 to notify the ASA network manager 714 if the ASA spectrum is no longer available, so that the ASA network can stop using that spectrum and the incumbent network controller 712 can obtain exclusive access to the ASA spectrum in real time.

The ASA network manager 714 may be embedded in a standard network element, depending on the core network technology. For example, if the ASA network is a long term evolution (LTE) network, the ASA network manager can be embedded in an operations, administration, and maintenance (OAM) server.

In FIG. 7, an incumbent network controller and a single ASA network manager are illustrated as being coupled to the ASA controller. It is also possible for multiple ASA networks (e.g., ASA network A, ASA network B and ASA network C) to be connected to an ASA controller 802, as in a system 800 shown in FIG. 8. ASA network A includes an ASA network A manager 814 coupled to the ASA controller 802, ASA network B includes an ASA network B manager 820 coupled to the ASA controller 802, and ASA network C includes an ASA network C manager 822 coupled to the ASA controller 802.

In this example, the multiple ASA networks may share the same ASA spectrum. The ASA spectrum may be shared via various implementations. In one example, the ASA spectrum is shared for a given region, so that each network is restricted to a subband within the ASA spectrum. In another example, the ASA networks share the ASA spectrum by using timing synchronization and scheduling the channel access of the different networks.

The system 800 may further include an incumbent network controller 812 of a primary user communicating with the ASA controller 802 via an ASA-1 interface 816, to provide incumbent protection information for a database 806. The ASA controller 802 may include a processor 804 coupled to a rules database 808 and ASA spectrum availability database 810. The ASA controller 802 may communicate with the ASA network managers 814, 820 and 822 via an ASA-2 interface 818. The ASA networks A, B, C may be secondary users.

The ASA network manager(s) may interact with various network elements, such as eNodeBs, to achieve the desired spectrum use control. The interaction may be implemented via the ASA-3 interface between eNodeBs in the RAN and an ASA network manager node embedded in an operations, administration, and maintenance server. The RAN may be coupled to a core network. An ASA controller may be coupled to the operations, administration, and maintenance server via an ASA-2 interface and to a network controller of a primary user via an ASA-1 interface.

In some cases, multiple incumbent network controllers are specified for the same ASA spectrum. That is, a single incumbent network controller may provide information about incumbent protection for a given ASA frequency band. Therefore, the architecture may be limited to a single incumbent network controller. However, it is noted that multiple incumbent network controllers may be supported. Still, it may be desirable to limit the network to a single incumbent network controller.

Spectrum Sharing systems, such as SAS, allow for radio resources (e.g., operating frequency, transmission power limits, and geographic areas) to be assigned dynamically among multiple users and service providers while providing some degree of protection of other users/service providers and incumbent users that potentially have higher priority (e.g., fixed satellite systems, WISPs, and government/military systems).

FIG. 9 illustrates an example architecture 900 of a spectrum sharing system. As illustrated, the spectrum sharing system may comprise one or more Spectrum Access Servers (SASs) (e.g., an ASA Controller) which are the entities that accept requests for radio resources from one or more Citizens Broadband Radio Service Devices (CBSDs), resolve conflicts or over-constraints in those requests, and grant the use of resources to radio access services.

When competing users and radio systems, (e.g., CBSDs) vie for radio resources, there is also a challenge of protecting these radio resources from each other based on restrictions due to the radio access technologies that are being used and a number of operational aspects for those radio access technologies. For example, some users/system operators may be able to coexist in the same or neighboring radio channels based on their use of the same (or compatible) radio technologies, compatible Self Organizing Network technologies, synchronized timing, common operational parameters (e.g., TDD slot structures, common radio silence intervals, etc.), and access to the same Core Networks for seamless mobility, etc. Accordingly, a SAS may determine channel assignments for different networks/system operators according to aspects presented herein.

Example Coverage Contour and Interference Thresholds Improvement for GAA Channel Assignment

As noted above, in a multi-tier commercial radio service (e.g., such as citizens broadband radio service (CBRS)), different tiers of operators may share portions of the same spectrum. In one reference example, different general authorized access (GAA) networks or technologies may be able to share different portions of the same bandwidth. For example, in such a case, one GAA network may be allocated 10 MHz of spectrum and another GAA network may be allocated 10 MHz of the same spectrum.

For GAA channel assignment among different networks in 3.5 GHz shared spectrum, a Spectrum Access Servers (SASs)/coexistence manager (CXM) may use the following method. For example, the SAS/CXM may first create a network overlap graph, where two networks are connected if there is an overlap in coverage between the two networks. The SAS/CXM may then color the graph with a minimum number of colors such that no two connected networks are assigned the same color. Each color represents a separate channel and the color of each network represents the channel assigned to the network.

In order to determine coverage overlap (e.g., which results in harmful interference) between two networks, the SAS/CXM may rely on coverage contours and interference thresholds (X,Y) from one network to another network. For example, coverage contour of a network may be referred to as the union of contours around Citizens Broadband Radio Service Devices (CBSDs) of that network based on received signal level (e.g., X dBm) from each CBSD. For example, a coverage contour threshold may be determined by considering a CBSD as a transmitter and basing the coverage contour threshold on the transmit power of the CBSD, propagation models, clutter, and indoor/outdoor information (e.g. building loss). A coverage contour may then be calculated around the CBSD where the received power from the CBSD is larger than the coverage contour threshold, X.

Additionally, an interference threshold may be referred to as a maximum allowable aggregated interference (e.g., Y dBm) from one network at the boundary or inside the coverage contour of another network. For example, according to aspects, if the interference from an example Network A is larger than the interference threshold at any point at the boundary or inside the coverage contour of another example network B, then networks A and B may be said to have coverage overlap and are connected in the network overlap graph. Aspects of the present disclosure present techniques for determining these thresholds so as to avoid negative effects associated with to aggressive or to conservative threshold values, as described below.

FIG. 10 illustrates example operations 1000 for assigning channels to a plurality of entities in a wireless communications environment. According to certain aspects, example operations 1000 may be performed, for example, by a network entity such a SAS (e.g., one or more of the SASs illustrated in FIG. 9), co-existence manager (CXM), or another network entity operating between SAS and CBSD (e.g., EMS illustrated in FIG. 9 or ASA controller 702 or 802 illustrated in FIGS. 7 and 8, respectively). According to aspects, the SAS, CXM, or other network entity may include one or more components (e.g., one or more processors and/or memory) configured to perform operations described herein.

Operations 1000 begin at 1002 by determining a coverage contour threshold and an interference threshold for each entity in the wireless communications environment. At 1004, the SAS decides whether a first entity and a second entity overlap in coverage based on the coverage contour threshold and the interference threshold for the first entity and the second entity, wherein the first entity and the second entity overlap if interference from the first entity is greater than the interference threshold for the second entity at any point at a boundary of or inside the coverage contour threshold of the second entity. At 1006, the SAS selects a channel assignment for the first entity and the second entity based on the decision, wherein selecting a channel assignment for the first entity and the second entity comprises assigning the first entity and the second entity orthogonal channels if the first entity and the second entity overlap in coverage. While not illustrated, operations 1000 may also include the SAS transmitting information to the first and second entity indicating the channel assignment.

As noted above, aspects of the present disclosure present techniques for determining coverage contour and interference thresholds so as to avoid negative effects associated with to aggressive (e.g., small threshold) or to conservative (e.g., large thresholds) threshold values. For example, an aggressive choice of the coverage contour and interference thresholds (X,Y) can result in ignoring some of the harmful interference in channel assignment (e.g., in coloring the graph). For example, when the coverage contour and interference thresholds (X,Y) are set too aggressively, a coexistence manager (CxM) may ignore some of the coverage overlap between networks, which results in interference after the channel assignment is done (e.g. networks A and B have coverage overlap, but CxM assigns them the same channel due to ignoring the coverage overlap because of the bad choice of thresholds). Therefore, too-aggressive thresholds may result in coverage holes and poor UE performance and increased interference.

A conservative choice of the coverage contour and interference thresholds (X,Y), in some cases, may result in many unnecessary connections in the network overlap graph for which too many colors in coloring the graph are needed (e.g., too many orthogonal channels). For examples, when the coverage contour and interference thresholds (X,Y) are set too conservatively, the CxM may assume coverage overlap between all networks and tries to unnecessarily orthogonalize them, which may result in small bandwidth to each of these networks. Therefore, too-conservative thresholds may result in small channels (i.e., channels with small bandwidth) for each network, resulting in poor network throughput and performance.

According to certain aspects, to resolve these issues and to determine coverage contour and interference thresholds that reduce interference yet maintain an acceptable throughput, the network entity (e.g., SAS/CXM/ASA) may first, in some cases, begin with a more conservative choice of (X,Y). According to certain aspects, if this choice results in too many colors (e.g., resulting in a bandwidth assigned to each network (e.g., color) below a bandwidth threshold), then the network entity may adjust the thresholds to be more aggressive, for example, until the number and bandwidth of the channels becomes reasonable (e.g., in some cases, 10 MHz), for example, which may be a function of an interference level, throughput, and of the particular type of technology of the network (e.g., LTE, LTE-A, new radio (NR), LTE-TD, MultiFire (MF), LAA/eLAA, etc.). According to aspects, a in some cases goal of the network entity may be to determine the coverage contour and interference thresholds such that the channel assigned to each network is larger than the bandwidth threshold (e.g., 10 MHz).

According to certain aspects, the SAS/CXM may use radio frequency (RF) measurements to help determine the thresholds (X,Y) to maximize throughput while reducing interference between networks. For example, the network entity may receive RF measurements from various CBSDs within the wireless communications environment. According to certain aspects, these RF measurements may include (but are not limited to) neighboring physical cell IDs (PCIs) and neighboring E-UTRAN Cell Global Identifier (ECGIs), as well as reference signal received power (RSRP)/received signal strength indicator (RSSI) measurements. Additionally, in some cases, these measurements can be network listen (NL) measurements through CBSDs or UE measurements. That is the network entity may listen for measurements taken by CBSDs or UEs within their respective networks, for example, to determine the RF distance and discover neighbors.

According to certain aspects, using these RF measurements, if a reported reference signal received power (RSRP) of cell-edge UEs in a network indicate a much larger/smaller coverage area than defined by the coverage contour threshold considered at the network entity (i.e., SAS/CXM), the thresholds can be adjusted by the network accordingly. For example, if the RSRP indicates a much larger coverage area than the coverage contour threshold considered at the network entity, the network entity may decrease the coverage contour threshold accordingly. According to aspects, decreasing the coverage contour threshold may result in increasing the area of contour, hence, providing protection to cell-edge UEs within the network. For example, if RSRP measurements indicate that some UEs are at located far enough such that the received power level of a base station of the network at a UE's location is −100 dBm while coverage threshold (based on which the coverage contour is defined) is −80 dBm (per 10 MHZ), the network entity may decrease the coverage threshold since the actual coverage area is larger than what the network entity originally considered.

Additionally, if CBSDs experience large interference through Received Signal Strength Indicator (RSSI) measurements, the network entity may adjust the thresholds (e.g., decrease to make the thresholds more conservative) accordingly to avoid harmful interference. Further, if a strong neighbor belonging to a different network is detected through NL/UE measurements operating in the same channel, this may indicate that the choice of thresholds is too aggressive, and the thresholds may be adjusted by the network entity to be more conservative accordingly.

Additionally, in some cases, the coverage contour and interference thresholds may be determined based on a tradeoff between signal-to-interference-plus-noise ratio (SINR) and throughput. For example, the network entity may receive SINR and throughput/bandwidth measurements from one or more devices (e.g., one or more UEs) in the wireless communications environment (e.g., CBSDs and/or UEs) and decide whether to adjust the threshold or not based on the SINR and throughput measurements. For example, for SINR measurements, if the network entity determines that the UE-SINR distribution indicated the overall performance/throughput in a network is “too good” (i.e., very little interference) it can make the threshold more aggressive to allow for larger bandwidth.

According to certain aspects, based on the received SINR and throughput measurements, the network entity may determine the coverage contour and interference thresholds according to BW*log(1+SINR), where BW is the bandwidth of a particular channel assigned to a CBSD and the SINR is the SINR for that particular channel. For example, using the equation noted above, the network entity may determine a beneficial change in the coverage contour and interference threshold. According to aspects, the network entity may consider a change in the thresholds as beneficial if the combination of change in SINR and resulting change in number of colors used in the color graph is beneficial (e.g., interference is reduced and throughput is increased).

Additionally, in some cases, the coverage contour and interference thresholds may be determined by the network entity as a function of CBSD density, for example, where CBSD density is based on GPS/location information received by the network entity from one or more CBSDs. For example, if the network entity determines that for a particular geographical location that there is a high density of CBSDs, the network entity may adjust the coverage contour and interference thresholds to be more conservative to reduce the interference observed between CBSDs.

According to certain aspects, due to some channel quantization impact, if the current number of colors results in unusable bandwidth, network entity may adjust the coverage contour and interference thresholds (X,Y) (and, as a result, adjust the network overlap graph) until a minimum number of colors used in the color graph results in usable bandwidth (e.g., for a particular type of technology), as explained below. According to aspects, whether a particular bandwidth is usable or non-usable may be based on predefined operating bandwidths of a network.

For example, assuming a total available GAA spectrum of 60 MHz and a minimum number of colors of 5 for current choice of (X,Y), the resulting channel bandwidth would be 60/5=12 MHz, which may not be usable in an long term evolution (LTE) system whose defined bandwidths are {1.4, 3, 5, 10, 15, 20} MHz. Thus, in some cases, the network entity may adjust the coverage contour and interference thresholds (X,Y) to be slightly more aggressive such that minimum number of colors becomes 4, thus resulting in a usable LTE channel bandwidth of 60/4=15 MHz and thereby obtaining the benefit of a larger bandwidth (e.g., as compared to 12 MHz). In other cases, the SAS/CXM may make the thresholds (X,Y) slightly more conservative such that minimum number of colors becomes 6, thus resulting in a usable LTE channel bandwidth of 60/6=10 MHz and thereby obtaining the benefit of reduced interference (e.g., as compared to 12 MHz).

According to certain aspects, the techniques presented above with respect to determining coverage contour and interference threshold between networks of a wireless communications environment may also be applied to inter-technology channel assignment and inter-CBSD channel assignment (as opposed to inter-network channel assignment described above) to determine the coverage overlap between different technologies or between different individual CBSDs (e.g., between LTE and WiMax or the like).

According to certain aspects, the network entity may also adjust the coverage contour and interference thresholds (X,Y) based on the percentage of overlaps between individual CBSDs determined based on coverage contour and interference thresholds (X,Y), and the area in which the overlap occurs between the individual CBSDs. For example, if there are many “small percentages of overlap” between CBSDs of two example networks, the network entity may adjust the coverage contour and interference thresholds slightly more aggressive to disconnect some of the connections in the graph. According to aspects, this can result in smaller required colors (larger channels) while not substantially increasing the interference.

FIG. 11 illustrates a communications device 1100 that may include various means-plus-function components configured to perform the operations illustrated in FIG. 10. According to aspects, the communications device 1100 may comprise a network entity, such as a SAS, CXM, or ASA or may be configured to perform functions associated with such network entities.

As shown, the communications device 1100 includes means 1102 for performing the operations illustrated at 1002 in FIG. 10. According to aspects, means 1102 may be configured to determine a coverage contour threshold and an interference threshold for each entity of a plurality of entities in the wireless communications environment.

Additionally, the communications device 1100 includes means 1104 for performing the operations illustrated at 1004 in FIG. 10. According to aspects, means 1104 may be configured to decide whether a first entity and a second entity overlap in coverage based on the coverage contour threshold and the interference threshold for the first entity and the second entity, wherein the first entity and the second entity overlap if interference from the first entity is greater than the interference threshold for the second entity at any point at a boundary of or inside the coverage contour threshold of the second entity.

Further, the communications device 1100 includes means 1106 for performing the operations illustrated at 1006 in FIG. 10. According to aspects, means 1106 may be configured to select a channel assignment for the first entity and the second entity based on the decision, wherein selecting a channel assignment for the first entity and the second entity comprises assigning the first entity and the second entity orthogonal channels if the first entity and the second entity overlap in coverage.

According to aspects, the means illustrated in FIG. 11 may comprise include various hardware and/or software/firmware component(s) and/or module(s), including, but not limited to a circuit, an application specific integrated circuit (ASIC), or processor, configured to perform the operations illustrated in FIG. 10.

As used herein, a phrase referring to “at least one of” a list of items refers to any combination of those items, including single members. As an example, “at least one of: a, b, or c” is intended to cover: a, b, c, a-b, a-c, b-c, and a-b-c, as well as any combination with multiples of the same element (e.g., a-a, a-a-a, a-a-b, a-a-c, a-b-b, a-c-c, b-b, b-b-b, b-b-c, c-c, and c-c-c or any other ordering of a, b, and c).

As used herein, the term “identifying” encompasses a wide variety of actions. For example, “identifying” may include calculating, computing, processing, deriving, investigating, looking up (e.g., looking up in a table, a database or another data structure), ascertaining and the like. Also, “identifying” may include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory) and the like. Also, “identifying” may include resolving, selecting, choosing, establishing and the like.

In some cases, rather than actually communicating a frame, a device may have an interface to communicate a frame for transmission or reception. For example, a processor may output a frame, via a bus interface, to an RF front end for transmission. Similarly, rather than actually receiving a frame, a device may have an interface to obtain a frame received from another device. For example, a processor may obtain (or receive) a frame, via a bus interface, from an RF front end for transmission.

The methods disclosed herein comprise one or more steps or actions for achieving the described method. The method steps and/or actions may be interchanged with one another without departing from the scope of the claims. In other words, unless a specific order of steps or actions is specified, the order and/or use of specific steps and/or actions may be modified without departing from the scope of the claims.

The various operations of methods described above may be performed by any suitable means capable of performing the corresponding functions. The means may include various hardware and/or software/firmware component(s) and/or module(s), including, but not limited to a circuit, an application specific integrated circuit (ASIC), or processor, as described above. Generally, where there are operations illustrated in Figures, those operations may be performed by any suitable corresponding counterpart means-plus-function components.

Those of skill in the art would understand that information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or combinations thereof.

Those of skill would further appreciate that the various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the disclosure herein may be implemented as electronic hardware, software/firmware, or combinations thereof. To clearly illustrate this interchangeability of hardware and software/firmware, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software/firmware depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present disclosure.

The various illustrative logical blocks, modules, and circuits described in connection with the disclosure herein may be implemented or performed with a general-purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

The steps of a method or algorithm described in connection with the disclosure herein may be embodied directly in hardware, in a software/firmware module executed by a processor, or in a combination thereof. A software/firmware module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, phase change memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such that the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a user terminal. In the alternative, the processor and the storage medium may reside as discrete components in a user terminal.

In one or more exemplary designs, the functions described may be implemented in hardware, software/firmware, or combinations thereof. If implemented in software/firmware, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A storage media may be any available media that can be accessed by a general purpose or special purpose computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD/DVD or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code means in the form of instructions or data structures and that can be accessed by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor. Also, any connection is properly termed a computer-readable medium. For example, if the software/firmware is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. Disk and disc, as used herein, includes compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and Blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.

The previous description of the disclosure is provided to enable any person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. Thus, the disclosure is not intended to be limited to the examples and designs described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein. 

What is claimed is:
 1. A method of assigning channels in a wireless communications environment, comprising: determining a coverage contour threshold and an interference threshold for each entity of a plurality of entities in the wireless communications environment; deciding whether a first entity and a second entity overlap in coverage based on the coverage contour threshold and the interference threshold for the first entity and the second entity, wherein the first entity and the second entity overlap if interference from the first entity is greater than the interference threshold for the second entity at any point at a boundary of or inside the coverage contour threshold of the second entity; and selecting a channel assignment for the first entity and the second entity based on the decision, wherein selecting the channel assignment for the first entity and the second entity comprises assigning the first entity and the second entity orthogonal channels if the first entity and the second entity overlap in coverage.
 2. The method of claim 1, wherein: the first entity comprises a first network or a first citizens broadband service device (CBSD); and the second entity comprises a second network or a second citizens broadband service device (CBSD).
 3. The method of claim 1, wherein determining the coverage contour threshold and the interference threshold for each entity in the wireless communications environment is based, at least in part, on a function of signal-to-interference-plus-noise ratio (SINR) and throughput.
 4. The method of claim 3, further comprising receiving SINR and throughput measurements from one or more devices in the wireless communications environment.
 5. The method of claim 3, wherein the coverage contour threshold and the interference threshold for each entity is determined according to: BW*log(1+SINR), where BW is the bandwidth of a particular channel assigned to a citizens broadband service device (CBSD).
 6. The method of claim 1, further comprising: receiving at least one of reference signal receive power (RSRP) or received signal strength indicator (RSSI) measurements; and wherein determining the coverage contour threshold and the interference threshold for each entity in the wireless communications environment is based on at least one of the RSRP or the RSSI measurements.
 7. The method of claim 6, wherein: the first entity comprises a first network and the second entity comprises a second network; and at least one of the RSRP or the RSSI measurements are received via a network listen procedure through a CBSD or through UE measurements from a UE in the wireless communications environment.
 8. The method of claim 1, wherein: the first entity comprises a first network and the second entity comprises a second network; and the coverage contour threshold and the interference threshold for each entity is a function of citizens broadband service device (CBSD) density based on location information of CBSDs in at least one of the first network or the second network.
 9. The method of claim 1, further comprising transmitting information to the first entity and the second entity indicating the channel assignment.
 10. The method of claim 1, further comprising adjusting the coverage contour threshold and the interference threshold for each entity if a current coverage contour threshold and a current interference threshold result in a bandwidth assigned to each entity below a threshold.
 11. The method of claim 10, wherein updating the coverage contour threshold and the interference threshold comprises making the coverage contour threshold and the interference threshold more aggressive.
 12. The method of claim 1, wherein the first entity comprises a first network and the second entity comprises a second network; and further comprising: determining the coverage contour threshold and the interference threshold resulting in a channel bandwidth to be assigned that is not useable by at least one of the first network or the second network; and adjusting the coverage contour threshold and the interference threshold to be either more aggressive or more conservative until a resulting channel bandwidth to be assigned is usable by at least one of the first network or the second network.
 13. The method of claim 12, wherein the channel bandwidth is determined to be unusable based on predefined operating bandwidths for at least one of the first network or the second network.
 14. The method of claim 1, wherein the first entity comprises a first network and the second entity comprises a second network; and further comprising: adjusting the coverage contour threshold and the interference threshold based on a percentage of overlap between individual citizens broadband service devices (CBSDs) in at least one of the first network or the second network.
 15. An apparatus for assigning channels in a wireless communications environment, comprising: at least one processor configured to: determine a coverage contour threshold and an interference threshold for each entity of a plurality of entities in the wireless communications environment; decide whether a first entity and a second entity overlap in coverage based on the coverage contour threshold and the interference threshold for the first entity and the second entity, wherein the first entity and the second entity overlap if interference from the first entity is greater than the interference threshold for the second entity at any point at a boundary of or inside the coverage contour threshold of the second entity; and select a channel assignment for the first entity and the second entity based on the decision, wherein selecting the channel assignment for the first entity and the second entity comprises assigning the first entity and the second entity orthogonal channels if the first entity and the second entity overlap in coverage; and a memory coupled with the at least one processor.
 16. The apparatus of claim 15, wherein: the first entity comprises a first network or a first citizens broadband service device (CBSD); and the second entity comprises a second network or a second citizens broadband service device (CBSD).
 17. The apparatus of claim 15, wherein the at least one processor is configured to determine the coverage contour threshold and the interference threshold for each entity in the wireless communications environment based, at least in part, on a function of signal-to-interference-plus-noise ratio (SINR) and throughput.
 18. The apparatus of claim 16, wherein the at least one processor is further configured to receive SINR and throughput measurements from one or more devices in the wireless communications environment.
 19. The apparatus of claim 18, wherein the at least one processor is configured to determine the coverage contour threshold and the interference threshold for each entity according to: BW*log(1+SINR), where BW is the bandwidth of a particular channel assigned to a citizens broadband service device (CBSD).
 20. The apparatus of claim 15, wherein the at least one processor is further configured to receive at least one of reference signal receive power (RSRP) or received signal strength indicator (RSSI) measurements; and wherein the at least one processor is further configured to determine the coverage contour threshold and the interference threshold for each entity in the wireless communications environment based on at least one of the RSRP or the RSSI measurements.
 21. The apparatus of claim 20, wherein: the first entity comprises a first network and the second entity comprises a second network; and at least one of the RSRP or the RSSI measurements are received via a network listen procedure through a CBSD or through UE measurements from a UE in the wireless communications environment.
 22. The apparatus of claim 15, wherein: the first entity comprises a first network and the second entity comprises a second network; and the coverage contour threshold and the interference threshold for each entity is a function of citizens broadband service device (CBSD) density based on location information of CBSDs in at least one of the first network or the second network.
 23. The apparatus of claim 15, wherein the at least one processor is further configured to transmit information to the first entity and the second entity indicating the channel assignment.
 24. The apparatus of claim 15, wherein the at least one processor is further configured to adjust the coverage contour threshold and the interference threshold for each entity if a current coverage contour threshold and a current interference threshold result in a bandwidth assigned to each entity below a threshold.
 25. The apparatus of claim 24, wherein the at least one processor is configured to adjust the coverage contour threshold and the interference threshold by adjusting the coverage contour threshold and the interference threshold to be more aggressive.
 26. The apparatus of claim 15, wherein: the first entity comprises a first network and the second entity comprises a second network; and the at least one processor is further configured to: determine the coverage contour threshold and the interference threshold resulting in a channel bandwidth to be assigned that is not useable by at least one of the first network or the second network; and adjust the coverage contour threshold and the interference threshold to be either more aggressive or more conservative until a resulting channel bandwidth to be assigned is usable by at least one of the first network or the second network.
 27. The apparatus of claim 26, wherein the channel bandwidth is determined to be unusable based on predefined operating bandwidths for at least one of the first network or the second network.
 28. The apparatus of claim 15, wherein: the first entity comprises a first network and the second entity comprises a second network; and wherein the at least one processor is further configured to: adjust the coverage contour threshold and the interference threshold based on a percentage of overlap between individual citizens broadband service devices (CBSDs) in at least one of the first network or the second network.
 29. An apparatus for assigning channels in a wireless communications environment, comprising: means for determining a coverage contour threshold and an interference threshold for each entity of a plurality of entities in the wireless communications environment; means for deciding whether a first entity and a second entity overlap in coverage based on the coverage contour threshold and the interference threshold for the first entity and the second entity, wherein the first entity and the second entity overlap if interference from the first entity is greater than the interference threshold for the second entity at any point at a boundary of or inside the coverage contour threshold of the second entity; and means for selecting a channel assignment for the first entity and the second entity based on the decision, wherein selecting the channel assignment for the first entity and the second entity comprises assigning the first entity and the second entity orthogonal channels if the first entity and the second entity overlap in coverage.
 30. A non-transitory computer-readable medium for assigning channels in a wireless communications environment, comprising: instructions that, when executed by at least one processor, configure the at least one processor to: determine a coverage contour threshold and an interference threshold for each entity of a plurality of entities in the wireless communications environment; decide whether a first entity and a second entity overlap in coverage based on the coverage contour threshold and the interference threshold for the first entity and the second entity, wherein the first entity and the second entity overlap if interference from the first entity is greater than the interference threshold for the second entity at any point at a boundary of or inside the coverage contour threshold of the second entity; and select a channel assignment for the first entity and the second entity based on the decision, wherein selecting the channel assignment for the first entity and the second entity comprises assigning the first entity and the second entity orthogonal channels if the first entity and the second entity overlap in coverage. 